Method of manufacturing a ball member usable in ball valves and other flow control devices

ABSTRACT

Disclosures include a method for manufacturing a ball member usable in a flow control valve. The method comprises connecting a workpiece to a rotating apparatus along an axis of rotation of the workpiece, simultaneously rotating the workpiece about the axis of rotation and moving a rotating cutting tool toward the axis of rotation along a second axis to form a first curved surface having a progressively shorter radius with respect to the axis of rotation, wherein the second axis is generally oriented perpendicular to the axis of rotation, and cutting a bore through the workpiece, wherein one end of the bore extends through the first surface and the other end of the bore extends through the second surface.

RELATED APPLICATION

This application is a divisional of and claims the benefit of domesticpriority to U.S. patent application Ser. No. 13/815,325, filed Feb. 21,2013, the entirety of which is incorporated herein by this reference.

FIELD

Embodiments usable within the scope of the present disclosure relate,generally, to methods usable for manufacturing ball valve components andother flow control valve components, and more particularly, but not byway of limitation, to a method of manufacturing a ball member having avariable radius.

BACKGROUND

Flow control valves, such as ball valves, are well known in the art andcommonly comprise a valve body or housing having an interior cavity anda pair of fluid flow channels extending through the housing. A ballmember is located within the cavity and is provided with an axialthroughbore, which is selectively aligned with, or disposed transverseto, the fluid channels in the housing, by rotating the ball member aboutan axis of rotation to control the flow of fluid through the fluidchannels. A pair of annular seats are located between the ball memberand the internal wall of the housing and are positioned about thethroughbore and the fluid channels to prevent fluids from leaking intothe interior cavity of the valve.

In valve arrangements of the aforementioned type, seat life and fluidleakage has been a reoccurring problem. Since the ball member isconstantly in sealing engagement with the seats, compressing them inboth the open and closed valve positions, the seats tend to wear outafter a period of time and need replacement. The problem is particularlymanifested when the valve is used to control flow of an abrasive fluid,when the fluid has a relatively high pressure, and/or when the valve isused under service conditions which require that the valve be rapidlycycled between open and closed positions. The same problem is present tosome degree in all types of ball valves in the course of fluid flowapplications. When the seats have become worn, they are otherwise nolonger capable of performing their intended sealing function and needreplacement to eliminate consequent leakage of fluid between the housingand the ball member. Replacement of the seats requires that the valve betaken out of service and new seals or seats be installed.

In an effort to deal with the foregoing problems, valve arrangementshave been designed that reduce seat loading when the valve is in itsopen position. For example, one ball valve design includes a split ball,wherein a cam, which rides within a split at the bottom of the ball,spreads the ball to form a tighter seal with the valve seats, as theball is rotated to its closed position. Other designs utilize plugs orball segments, which seal against a single seat in the housing, andwhich are mounted eccentrically on an actuator shaft or a stem, so thatthe plug is moved into forcible contact with the seat in the closedposition of the valve. Moving the valve to the open position moves theplug away from the seat, allowing fluid to flow through the valve.

Valves employing the split ball design or eccentrically offset plugsare, however, relatively complicated and expensive to manufacture andmaintain. Eccentrically mounted plugs also suffer from otherdisadvantages, since they involve an asymmetrical or unbalanced design.Specifically, eccentrically mounted plug valves are prone to leakingproblems arising from rapid internal component wear, resulting from lackof structural support to counter forces created by high fluid pressures.

Therefore, there is a need for a fluid flow control valve that obviatesall the above problems by providing a novel ball member having asymmetrical and balanced design, improving the internal structuralsupport to counter forces created by high fluid pressures.

There is also a need for a ball member comprising an outer surfacehaving a gradually increasing radius with respect to the axis ofrotation. As the ball member rotates from the open valve position to theclosed valve position, the outer surfaces gradually seal against a pairof associated upstream and downstream valve seats, to achieve maximumseal loading at the full closed valve position.

There is also a need for an improved ball member configured for use withconventional valve housing and seats, while improving valve life andsealing performance of the valve.

SUMMARY

Embodiments usable within the scope of the present disclosure relate,generally, to a method for manufacturing a ball member usable in a flowcontrol valve. One such method comprises the steps of forming a firstspherical portion of the ball member by moving a rotating cutting tooltoward an axis of rotation along an axis of the cutting tool androtating the workpiece about 180 degrees about the axis of rotation.Forming a second spherical portion of the ball member comprises moving acutting tool toward the axis of rotation along the axis of the cuttingtool and rotating the workpiece about 180 degrees about the axis ofrotation. The steps comprising forming the first and second curvedportions may be performed simultaneously. The method may include thestep of moving the cutting tool generally perpendicular to both the axisof the cutting tool and the axis of rotation away from a point ofintercept of said axes for about a first 90 degrees of rotation of theworkpiece and towards the point of intercept of said axes for about asecond 90 degrees of rotation of the workpiece. An embodiment of themethod may also include steps of forming a variable radius of the ballmember relative to the axis of rotation. The method for manufacturing aball member may also include the steps of machining the workpiece toform a first cylindrical protrusion along the axis of rotation andmachining the workpiece to form a second cylindrical protrusion alongthe axis of rotation opposite the first cylindrical protrusion.

Embodiments usable within the scope of the present disclosure furtherrelate to another method for manufacturing a ball member from aworkpiece, wherein the method may comprise the steps of connecting theworkpiece to a rotating apparatus at a first connection point of theworkpiece and at a second connection point of the workpiece, rotatingthe workpiece along a first axis, moving a rotating cutting tool along asecond axis toward the workpiece, cutting the workpiece partiallybetween the first connection point and the second connection point,further moving the rotating cutting tool along the second axis towardthe workpiece, further cutting the workpiece partially between the firstconnection point and the second connection point, and cutting a borethrough the workpiece, wherein the bore extends through the firstsurface and through the second surface. In the embodiment of the method,the step of cutting the workpiece partially between the first connectionpoint and the second connection point may comprise the steps of forminga second surface extending partially between the first connection pointand the second connection point, forming an another portion of the firsttrunnion on a first side of the second surface, and forming an anotherportion of the second trunnion on a second side of the second surface.In the method embodiment, the step of forming a second surface extendingpartially between the first connection point and the second connectionembodiment of the method may comprise the steps of forming a secondsurface extending partially between the first connection point and thesecond connection point, forming an another portion of the firsttrunnion on a first side of the second surface, and forming an anotherportion of the second trunnion on a second side of the second surface.

Embodiments usable within the scope of the present disclosure relate toyet another method for manufacturing a ball member usable in a flowcontrol valve. The method may comprise the steps of connecting aworkpiece to a rotating apparatus along an axis of rotation of theworkpiece, simultaneously rotating the workpiece about the axis ofrotation and moving a rotating cutting tool toward the axis of rotationalong a second axis to form a first curved surface having aprogressively shorter radius with respect to the axis of rotation,moving the rotating cutting tool along the second axis away from theworkpiece, further simultaneously rotating the workpiece about the axisof rotation and moving the rotating cutting tool toward the axis ofrotation along the second axis to form a second curved surface having aprogressively shorter radius with respect to the axis of rotation, andcutting a bore through the workpiece, wherein one end of the boreextends through the first surface and the other end of the bore extendsthrough the second surface.

The foregoing is intended to give a general idea of the invention, andis not intended to fully define nor limit the invention. The inventionwill be more fully understood and better appreciated by reference to thefollowing description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

In the detailed description of various embodiments usable within thescope of the present disclosure, presented below, reference is made tothe accompanying drawings, in which:

FIG. 1 depicts a cross sectional side view of an embodiment of thedevice usable within the scope of the present disclosure, which includesan embodiment of the ball valve in the open valve position.

FIG. 2 depicts a cross sectional front view of an embodiment of thedevice usable within the scope of the present disclosure, which includesan embodiment of the ball valve in the open valve position.

FIG. 3A depicts a cross sectional top view of an embodiment of thedevice usable within the scope of the present disclosure, which includesan embodiment of the ball valve in the open valve position.

FIG. 3B depicts a cross sectional top view of an embodiment of thedevice usable within the scope of the present disclosure, which includesan embodiment of the ball valve in the closed valve position.

FIG. 4 depicts a cross sectional close-up view of an embodiment of thedevice usable within the scope of the present disclosure, which includesan embodiment of the ball valve seats in the open valve position.

FIG. 5A depicts an isometric view of an embodiment of the device usablewithin the scope of the present disclosure, which includes an embodimentof the ball member.

FIG. 5B depicts an isometric view of an embodiment of the device usablewithin the scope of the present disclosure, which includes an embodimentof the ball member.

FIG. 6A depicts a top view of an embodiment of the device usable withinthe scope of the present disclosure, which includes an embodiment of theball member.

FIG. 6B depicts a top view of an embodiment of the device usable withinthe scope of the present disclosure, which includes an embodiment of theball member.

FIG. 7 depicts an isometric view of an embodiment of the device usablewithin the scope of the present disclosure, which includes a fly cutterand an embodiment of the ball member.

DETAILED DESCRIPTION OF EXAMPLE EMBODIMENTS

Before describing selected embodiments of the present disclosure indetail, it is to be understood that the present invention is not limitedto the particular embodiments described herein. The disclosure anddescription herein is illustrative and explanatory of one or moreembodiments and variations thereof, and it will be appreciated by thoseskilled in the art that various changes in the design, organization,order of operation, means of operation, equipment structures andlocation, methodology, and use of mechanical equivalents may be madewithout departing from the scope of the invention.

As well, it should be understood that the drawings are intended toillustrate and plainly disclose selected embodiments to one of skill inthe art, but are not intended to be manufacturing level drawings orrenditions of final products and may include simplified conceptual viewsas desired for easier and quicker understanding or explanation. As well,the relative size and arrangement of the components may differ from thatshown and still operate within the scope of the invention. It shouldalso be noted that like numbers appearing throughout the variousembodiments and/or figures represent like components.

Moreover, it should also be understood that various directions such as“upper,” “lower,” “bottom,” “top,” “left,” “right,” and so forth aremade only with respect to explanation in conjunction with the drawings,and that the components may be oriented differently, for instance,during transportation and manufacturing as well as operation. Becausemany varying and different embodiments may be made within the scope ofthe concepts herein taught, and because many modifications may be madein the embodiments described herein, it is to be understood that thedetails herein are to be interpreted as illustrative and non-limiting.

Embodiments usable within the scope of the present disclosure relate,generally, to ball valves and other valves used to control the flow offluids, and more particularly, but not by way of limitation, to a ballmember configuration having a variable radius with respect to its axisof rotation, which results in a variable force being exerted against thevalve seats as the ball member is turned between the open and closedpositions, thereby changing the sealing pressure between the ball memberand the valve seats and increasing the life of the valve seats.

Referring now to FIGS. 1, 2, 3A, and 3B, an embodiment of a fluid ballvalve in accordance with the present invention is generally depicted.The ball valve (10) comprises, in general, a valve body or a housing(20), a top cover or a bonnet (22), a rotating actuation member or astem (40), seats (30 a, 30 b), and a generally spherical shaped flowrestricting member or a ball member (50).

The housing (20) may be arranged to have any of several well-knownexternal configurations and as depicted in FIGS. 1, 2, 3A, and 3B. Atthe center of the housing (20) is a generally spherical chamber, calleda housing cavity (24), which encompasses the ball member (50). Thehousing further comprises a pair of fluid channels (21 a, 21 b)extending through the housing, on opposite sides of the central cavity(24). The fluid channels (21 a, 21 b) define an axial fluid passagewaythrough the housing (20), enabling fluid transfer between external fluidconduits (not shown) or other equipment connected to the valve (10). Thefluid channels (21 a, 21 b) may be configured to terminate with spacedflanges (23 a, 23 b), as depicted in FIGS. 1, 3A, and 3B, each of whichmay be connected to external fluid conduits (not shown) or otherequipment, by bolts or by other means, such as threaded connectors (notshown). While the housing (20) need not be symmetrical as depicted, itis often desirable that the valve permits complete symmetry inorientation of installation. Thus, a ball valve (10) may be connectedinto a fluid system without regard to which flange (23 a, 23 b) is beingconnected to the pressure side of the fluid line.

As depicted in the embodiment of FIGS. 1 and 2, enclosing the topopening in the valve cavity is a bonnet (22), shown as a generally roundand symmetrical plate member. The center of the bonnet (22) contains anaperture (41) of sufficient diameter to accommodate a valve actuatingmember, or a stem (40), extending therethrough in a perpendicularorientation relative to the top surface of the bonnet (22). The centralaperture (41) contains a counterbore section, defining an uppercylindrical cavity (42), formed coaxially with the aperture (41) andlocated at the lower end of the aperture (41). The upper cylindricalcavity (42) structurally retains and supports portions of the stem (40)and the ball member (50). The upper portion of the valve stem (40)extends beyond the aperture (41) and terminates with an upper stem drivemember (43), which is configured for connection with a valve actuator(not shown). The stem (40) may be rotated by means of a handle (notshown) attached to the upper stem drive member (43), allowing selectiverotation of the ball member (50) between the open valve position shownin FIGS. 1, 2, and 3A, and the closed valve position shown in FIG. 3B.The actuation of the stem (40) may also be automated, whereby therotation is performed by a fluid powered or electrical rotary actuator(not shown) attached thereto.

The lower portion of the valve stem terminates with an annular supportring (44), which extends radially from the lower portion of the valvestem (40). The annular support ring (44) engages the lateral surface ofthe upper cavity (42) to maintain the coaxial alignment between thevalve stem (40) and the bonnet aperture (41). The annular support ring(44) also engages the upper surface of the upper cavity (42) to retainthe valve stem (40) within the bonnet aperture (41) and to maintainengagement with the ball member (50). The upper cavity (42) isconfigured to receive both the support ring (44) as well as the uppertrunnion (56). As in the depicted embodiment, the upper cavity (42) mayhave varying diameters in order to accommodate a support ring (44) andan upper trunnion (56) having different diameters.

As further depicted in FIGS. 1 and 2, sealing members (45) occupy theannular space between the stem (40) and the bonnet (22). These annularsealing members (45) perform the usual function of packing the stem (40)and may be fabricated from any known sealing or packing materials andconfigured in any manner known in the art, including, but limited to,elastomer O-ring seals, cup seals, polymer seals, composite seals, andmetal seals.

The top portion of the housing (20) terminates with a ridge (25), whichdefines a valve cavity opening (26). The ridge (25) comprises theconnection means for mounting of the bonnet (22) to the housing (20) ina secured and sealed relation. FIGS. 1 and 2 depict the means forconnection to be in the form of a flange connection, securing the bonnet(22) to the housing (20) by means of a plurality of retainer threadedstud and nut assemblies (27). Although the figures depict oneembodiment, it is not intended to limit the scope of the presentinvention to a bolted bonnet (22) construction. A number of bonnetconnection systems (not shown) are commercially available at the presenttime and may be employed to secure a bonnet member, in sealed andpositively retained assembly, with a valve body.

Referring again to FIGS. 1, 3A, and 3B, the embodiments depicted show apair of annular sealing instruments, called seats (30 a, 30 b), whichare supported against the housing (20) and located about the fluid flowchannels (21 a, 21 b). Located at the inside terminus of each fluidchannel (21 a, 21 b) is a seat shoulder (28 a, 28 b) usable to supportthe seats (30 a, 30 b) in position. Each seat shoulder (28 a, 28 b) maybe shaped and proportioned to retain the corresponding seat (30 a, 30 b)in place during operation, preventing the seats from shifting whenengaged with the ball member (50). The seats (30 a, 30 b), usable withinthe disclosed ball valve (10), may be of any type known in the industry.Among the seat configurations usable with the disclosed ball member (50)are double-block and bleed (DBB) and double-isolation and bleed (DIB)seat types, such as defined by API 6D/ISO 14313 design specifications.

FIGS. 1, 3A, 3B, and 4 depict DIB seats (30 a, 30 b) as one embodimentof the seats (30 a, 30 b) usable with the currently disclosed ballmember (50). DBB valves typically contain two unidirectional seats (notshown). The unidirectional seats, when energized, isolate the pressurein the flow channels (21 a, 21 b) from the housing cavity (24) betweenthe seats. If pressure is reversed, the seats are urged away from theball member (50) and allow pressure to relieve from the housing cavity(24) to the flow channels (21 a, 21 b). This is a desirable function,particularly in liquid service. In the case where the valve housingcavity (24) is filled with liquid and heated due to process flow orexternal sources, pressure may build due to thermal expansion of theliquid in the housing cavity (24). Without the self-relievingunidirectional seats, this could lead to over-pressure in the valvecavity (24) resulting in leakage or rupture. DIB valves include one ortwo bidirectional seats (30 a, 30 b), as depicted in FIGS. 1, 3A, 3B,and 4. When two bidirectional seats (30 a, 30 b) are used, the valveprovides double isolation from pressure at either flow channel (21 a, 21b). This configuration has one operational drawback in that it may notrelieve pressure in the housing cavity (24) past the seats (30 a, 30 b).An external relief piping system (not shown) may be used to allow anypressure build-up in the housing cavity (24).

The action of the seats is determined by the pressure differentials thatact on the seats. For the unidirectional seat (not shown), upstreampressure urges the seat against the ball member (50) and creates a sealbetween the seat and the ball member (50). Pressure in the housingcavity (24), on the other hand, urges the seat away from the ball member(50), breaking the seal between the ball member (50) and the seat,thereby relieving pressure within the housing cavity (24). Conversely,the bidirectional seats (30 a, 30 b) are urged against the ball member(50) by pressure regardless of the location of the pressure source,whether it's the fluid channel (21 a, 21 b) or the housing cavity (24).The DIB feature provides a second fluid flow barrier, such that whilepiping is removed downstream (as in a repair situation), the housingcavity (24) may be monitored for upstream seat leakage. The downstreamseat provides the second barrier in the event the upstream seat beginsleaking during the maintenance or repair.

FIG. 4 depicts a close-up view of one embodiment of a DIB seat (30 a)usable within the scope of the current disclosure. The first seat (30 a)comprises a plurality of seat segments (31, 32, 33) and a plurality ofsealing elements (35, 36, 37), assembled to form the first seat (30 a).The rear seat segment (32) is positioned against the first housingshoulder (28 a) and encompasses the first sealing element (37) (e.g., anO-ring), which seals against the first shoulder (28 a), limiting leakageadjacent to the shoulder. The interior seat segment (31) is alsopositioned against the first housing shoulder (28 a), but is longer andextends past the rear seat segment (32). A second sealing element (36)is located between the rear seat segment (32) and the interior seatsegment (31), limiting fluid leakage therebetween. An exterior seatsegment (33) is located around the rear and interior seat segments (32,31), with a third sealing element (35), called an insert, locatedbetween the exterior seat segment (33) and the ball member (50),limiting fluid leakage adjacent to the ball member (50).

The embodiment of the first seat (30 a) depicted in FIG. 4, is anexample of a floating and expandable seat usable with the valve (10) andthe ball member (50) of the current disclosure. A floating andexpandable seat design allows a uniform sealing action against surfaces,which may be unevenly placed against the seat. For example, in theclosed ball valve position, one side of the ball member (50) may bepositioned closer to one side of the housing shoulder (28 a), resultingin greater compression of one side of the seat (30 a). The disclosedfloating and expandable seat design allows the seat (30 a) to movetowards or away, as well as sideways, from the ball member (50) andtherefore adjust to uneven contact with the ball member (50), resultingin a generally uniform seat loading by the ball member (50). Althoughone embodiment of a floating seat is depicted in FIG. 4, any floatingand expandable seat design known in the industry may be used with theball valve (10) and the ball member (50) disclosed in the currentapplication.

Also depicted in FIG. 4 is a first retainer (34 a), which maintains thefirst seat (30 a) in a generally constant position between the firstshoulder (28 a) and the ball member (50). As further depicted in FIG. 1,the first retainer (34 a) may be held in position by connecting it to alower portion of the bonnet (22), by use of any known means, such asthreaded bolts, for example.

Located within the housing cavity (24) is a fluid flow obstruction,called the ball member (50). As depicted in FIGS. 5A and 5B, the ballmember (50) has a generally spherical or round shape comprising twopartially spherical members, called spherical segments (51 a, 51 b), athroughbore (55), an upper trunnion (56), and a lower trunnion (57). Theball member (50) is adapted to be rotated about its axis of symmetry(X), which runs vertically through the center of the upper and lowertrunnions (56, 57). The throughbore (55) extends transversely throughthe ball member (50) and functions as a fluid passageway, when each endor rim (66 a, 66 b) of the throughbore (55) is aligned with each fluidchannel (21 a, 21 b), as depicted in FIG. 1. Therefore, the ball member(50) allows communication between the fluid channels (21 a, 21 b) whenactuated to the open position and disconnects the fluid channels (21 a,21 b) when actuated to the closed position, as in a typical ball valvearrangement.

Referring again to FIGS. 1, 2, 3A, and 3B depicts one embodiment of afluid flow control valve. The figures are not intended to limit thescope of the present invention to that construction as other designs arecommercially available at the present time and may be employed withoutdeparting from the scope of the disclosed invention. Specifically, FIG.1 depicts a ball valve embodiment comprising a throughbore (55) andfluid channels (21 a, 21 b) having a coaxial configuration; however,these fluid channels (21 a, 21 b) may be offset or oriented at arelative angle therebetween and/or in relation to the throughbore (55).Furthermore, the ball member (50) according to the present disclosuremay also comprise a full port or restricted port design. Therefore, thediameter of the throughbore (55) depicted may be equal to, smaller than,or greater than the diameter of the fluid channels (21 a, 21 b).

FIGS. 1 and 2 also depict a ball member (50) having upper and lowertrunnions (56, 57), which function as mounting and pivoting points forthe ball member (50). As the ball member (50) is actuated between theopen and closed positions, it rotates within a cylindrical cavity (42)at its upper end and about a cylindrical protrusion (29) at its lowerend. As stated above, the upper cylindrical cavity (42) is fashioned asa counterbore, located at the lower portion of the bonnet aperture (41).The upper cylindrical cavity (42) receives the upper trunnion (56),while the cylindrical protrusion (29) extends upwardly from the housing(20) into the housing cavity (24), mating within a lower cylindricalcavity (58) in the lower trunnion (57). In the depicted embodiment, theupper trunnion (56) comprises two sections, an upper section, which isinserted into the upper cylindrical cavity (42) as described above, andthe lower section, which comprises an outside diameter that is largerthan the upper cylindrical cavity (42). The lower section of the uppertrunnion contacts the bottom surface of the bonnet (22) to retain theball member (50) in proper vertical position within the housing cavity(24) during operation. The upper and the lower trunnions (56, 57), theupper cylindrical cavity (42), and the cylindrical protrusion (29) arearranged coaxially, resulting in the ball member having an axis ofrotation (X) located through the center of the trunnions (56, 57).

FIGS. 1, 2, 5A, and 5B depict upper and lower trunnions (56, 57)integrally formed with the spherical segments (51 a, 51 b) locatedtherebetween. Such integral construction may be achieved through severaltechniques known in the art, such as, for example, casting the entireball member (50) as a single piece or by using a milling machine to cutthe entire ball member (50) from a single workpiece. Manufacturingprocesses usable to construct the ball member of the current disclosureare described in additional detail below.

In addition to supporting the ball member (50), the upper trunnion (56)also contains a cavity, or a stem receptacle (59), designed to mate withthe stem (40), thereby enabling actuation of the ball member (50). Thebottom portion of the valve stem (40), called the drive member (46),projects downwardly and engages within the stem receptacle (59). Thestem receptacle (59) has a generally rectangular shape configured toreceive the drive member (46). The stem receptacle (59) defines a stemconnection, which may be in the form of a depression or receptacle ormay have any other geometric form that compliments the drive member (46)and permits a non-rotatable relationship to be established between theball member (50) and the stem (40), and may have other suitable geometrywithin the scope of the present invention. In an alternate embodiment,ball member (50) may be provided with a protruding member thatestablishes non-rotatable driving relation with the valve stem (40),which may be provided with a depression or a receptacle.

In addition to providing the pivoting points for the ball member (50),the upper and lower trunnions (56, 57), the upper cylindrical cavity(42), and the cylindrical protrusion (29) provide the ball member (50)with mounting surfaces, giving the ball member (50) structural supportto withstand high fluid pressures, without resulting in fluid leakage orinternal damage. During operation, especially in the closed valveposition, the surface of the ball member (50) may be exposed to highfluid pressures. These pressures may generate large forces on the ballmember (50), resulting in significant internal stresses being exertedupon its support structure. Certain valve designs, such as a floatingball design (not shown), may provide insufficient structural support,resulting in the ball member being shifted, causing fluid leaks into thevalve cavity or the outlet port. Excessive shifting of the ball membermay also result in damage to the trunnions, the stem, and internalseals. The trunnions (56, 57), the upper cylindrical cavity (42), andthe lower cylindrical protrusion (29), as depicted in FIGS. 1 and 2,provide internal support for the ball member (50), maintaining it alongthe axis of rotation (X) and preventing excessive undesired movement ofthe ball member (50).

Although, in the embodiment depicted in FIGS. 1 and 2, the bottomtrunnion (57) of the ball member (50) contains a bottom cylindricalcavity (58) for allowing the ball member (50) to rotate about acylindrical protrusion (29) in the housing (20), other trunnion designsmay be incorporated. For example, in one alternate embodiment (notshown), the lower trunnion does not contain a cavity, but comprises asolid cylindrical protrusion that sits within a cylindrical cavityformed within the lower internal surface of the housing. In thisconfiguration, the lower trunnion is engaged within the cylindricalcavity, allowing the ball member to rotate about the axis of rotationwhile providing structural support to the ball member.

As previously stated and depicted in embodiments of FIGS. 5A and 5B, theball member (50), in accordance with the present disclosure, furthercomprises two spherical segments (51 a, 51 b). These spherical segments(51 a, 51 b) comprise partial spheres of like shape and size, which areoffset and integrally joined together, and disposed symmetrically to oneanother relative to the axis of rotation (X). A bore (55) extendsthrough the joined first and the second spherical portions, wherein thefirst terminus of the throughbore (55) is located on the first sphericalsegment (51 a) and the second terminus of the throughbore (55) islocated on the second spherical segment (51 b). The throughbore (55) isoriented generally perpendicular to the axis of rotation. However, inalternate embodiments, the throughbore (55) may be oriented in atraverse manner relative to the axis of rotation.

Furthermore, in the embodiments of the ball member (50) shown in FIG.6A, depicting the top view of the ball member (50), each sphericalsegment (51 a, 51 b) comprises a center of sphere, called an offsetpoint (58 a, 58 b), as each center of sphere is offset from the ballmember's axis of rotation (X). Each offset point (58 a, 58 b) is locatedon either side of axis of rotation (X) along the longitudinal axis (Z)of the throughbore (55). Each spherical segment (51 a, 51 b) exhibits aradius (61 a, 61 b) with respect to its respective offset point (58 a,58 b), located along the longitudinal axis (Z) of the throughbore (55)at a specific offset distance (62 a, 62 b) from the axis of rotation(X). Due to the offset distances (62 a, 62 b), the two offset points (58a, 58 b), marking the centers of each spherical segment (51 a, 51 b),are shifted from each other by a distance comprising the sum of thefirst and second offset distances. Although FIG. 6A depicts anembodiment of the ball member (50) having offset points (58 a, 58 b)located along the longitudinal axis (Z), alternate embodiments of theball member (50) may comprise offset points being located in variouspoints along the Y-Z plane. The specific location of the offset points(58 a, 58 b) define the orientation of each spherical segment (51 a, 51b) relative to the other, which affects the height of the shoulders (54a, 54 b) and the characteristics of the radius (65 a, 65 b, see FIG. 6B)of the ball member (50) with respect to the axis of rotation (X).

As further depicted in FIG. 6A, because the two spherical segments (51a, 51 b) are offset, there exist two areas of separation, calledshoulders (54 a, 54 b), located between the spherical segments (51 a, 51b) at the points where one spherical segment transitions to the other.The two shoulders (54 a, 54 b) are of like configuration, located onopposite sides of the ball member (50), wherein each shoulder is locatedsymmetrically, with respect to the other, relative to the ball's axis ofrotation (X). In the depicted embodiment, the shoulders (54 a, 54 b) areoriented generally perpendicular to the longitudinal axis (Z) of thethroughbore. In the same embodiment, the shoulders (54 a, 54 b) may beoriented generally parallel with the rims (66 a, 66 b) of thethroughbore (55).

Referring now to FIGS. 6A and 6B, an embodiment of the ball member (50)in accordance with the present disclosure is depicted. Although eachspherical segment (51 a, 51 b) has a radius (61 a, 61 b) with respect toits offset point (58 a, 58 b), and exhibits a progressively increasing(or decreasing depending on direction) radius, called variable radius(65 a, 65 b), with respect to the axis of rotation (X), whereby themaximum radius is located at the top of the shoulder (54 a, 54 b) andthe minimum radius is located at the bottom of the shoulder (54 a, 54b). The surface area adjacent to the top of the shoulder (54 a, 54 b) iscalled the high surface area (52 a, 52 b), and the surface area adjacentto the bottom of the shoulder (54 a, 54 b) is called the low surfacearea (53 a, 53 b). As depicted in the embodiment in FIGS. 6A and 6B, thethroughbore (55) penetrates the ball member through the low surface area(53 a, 53 b) of each spherical segment (51 a, 51 b). As a result, eachlow surface area (53 a, 53 b) of the ball member is truncated along thelongitudinal axis (Z) of the throughbore (55).

As depicted in FIGS. 5A and 5B, the shape of the surface area of eachspherical segment (51 a, 51 b) is further defined by the upper and lowertrunnions (56, 57) extending from the ball member (50), having thespherical segments (51 a, 51 b) located therebetween. Specifically, theupper and lower boundaries of the surface areas of each sphericalsegment (51 a, 51 b) are defined by the trunnions (56, 57), whereby theupper and lower boundaries (i.e., edges) of the surface area of eachspherical segment (51 a, 51 b) curve about the upper and lowertrunnions. The lateral boundaries of the surface area of each sphericalsegment (51 a, 51 b), defined by the shoulders (54 a, 54 b), curveadjacent to the first and second rim (66 a, 66 b) of the throughbore(55). Specifically, the first lateral outwardly curving boundary (notshown) of the surface area of the first spherical segment (51 a) curvesoutwardly (i.e., a convex boundary), around the far side of the firstrim (66 a), thereby encompassing the first rim (66 a), while theopposite lateral inwardly curving boundary (68 a) (i.e., a concaveboundary) into the surface area, adjacent the near side of the secondrim (66 b), thereby excluding the second rim (66 b). The shape of thespherical area of the second spherical segment (51 b) has a similarshape, comprising an outwardly curving boundary (67 b) (i.e., convexboundary) encompassing the second rim (66 b) and an inwardly curvingboundary (not shown) (i.e., concave boundary) excluding the first rim(66 a). Therefore, if the surface area of each spherical segment (51 a,51 b) was unrolled or its curvature about the axis of rotation (X) wasstraightened, the surface area of each spherical segment (51 a, 51 b)would have an elongated lune-like shape, wherein the concave and convexboundaries are separated by an additional area therebetween.

Referring now to FIG. 6B, the outer point (63 a, 63 b) of each shoulderinitiates at a predetermined angle (64 a, 64 b) relative to thelongitudinal axis (Z) of the throughbore (55), wherein each shoulder (54a, 54 b) outlines a throughbore opening along a plane perpendicular tothe throughbore axis (Z). In the depicted embodiment, the outer point(63 a, 63 b) of each shoulder (54 a, 54 b) is located at an angle (64 a,64 b) relative to the axis (Z) of the throughbore (55). The height ofeach shoulder (54 a, 54 b) may be defined as the difference between themaximum and minimum radius (56 a, 56 b) of the ball member (50) adjacentto the shoulder (54 a, 54 b). The relative dimensions of the shoulders(54 a, 54 b) and the offset distances (62 a, 62 b), as depicted in FIG.6A, are exaggerated for clarity, and in actual embodiments the height ofeach shoulder is very small. For example, in one embodiment, the ballmember may have a sphere radius (61 a, 61 b) of 3.500 inches, an offsetdistance (62 a, 62 b) of 0.030 inches, a shoulder (54 a, 54 b) height of0.060 inches, and the shoulder angle (64 a, 64 b) of 37.000 degrees.

Although the two spherical segments (51 a, 51 b) are described as beingseparate and distinct, the ball member (50) has a unitary configuration,wherein the two spherical segments (51 a, 51 b) are integrally formed.The outside surface of each spherical segment (51 a, 51 b) defines asealing surface of the ball member (50), comprising a smooth finish,which enables it to form a fluid seal when compressed against the valveseats (30 a, 30 b) during operation. The spacing of the offset points(58 a, 58 b) relative to the axis of rotation (X) provides the ballmember (50) with eccentric properties. Wherein each spherical segment(51 a, 51 b) comprises a radius (61 a, 61 b) with respect to itscorresponding offset point (58 a, 58 b), each spherical segment (51 a,51 b) may be eccentric with respect to the axis of rotation (X),enabling the ball member (50) to progressively increase contact forceagainst the seats (30 a, 30 b). As the ball member (50) is rotated aboutthe axis of rotation (X), which is traverse or generally perpendicularto the longitudinal axis (Z) of the throughbore (55), each sphericalsegment (51 a, 51 b) contacts a corresponding seat (30 a, 30 b) withprogressively increasing or decreasing force. The operation of the valveis described in more detail below.

While the first and second spherical segments are defined above ascomprising partial spheres of like shape and size, alternate embodimentsexist, wherein each spherical segment comprises a spherical shape or anyother rounded shape that may not be spherical. Specifically, thespherical segments may be generally rounded segments, comprisingthree-dimensional curved surfaces, having circular, elliptical, oval,spiral, or other curvatures. Although the generally rounded segments maynot contain singular centers that are offset relative to the axis ofrotation, the segments may be offset from one another and integrallyjoined, having the curved surfaces oriented away from each other. Thegenerally rounded segments may also be disposed symmetrically, to oneanother, with respect to the axis of rotation.

The ball member (50), in accordance with the present disclosure asdescribed above, may be incorporated into valve bodies havingalternative designs and/or standard valve bodies known in the industry.One alternative embodiment (not shown) includes a ball valve, having avalve body comprising a bottom opening, whereby the bottom of the bodyis closed by a flanged cover. The internal surface of the valve bodydefining the valve cavity may comprise cylindrical cavities, asdescribed in the embodiment depicted in FIGS. 1, 2, 3A, and 3B; however,the ball member may be installed in the valve cavity through the bottomopening. The upper trunnion (56) of the ball member may be inserted intoa corresponding upper cylindrical cavity, while the lower trunnion (57)may be supported by a cylindrical protrusion or a bottom cylindricalcavity located within the bottom flange cover. The ball valve mayotherwise be configured in the manner described above and depicted inFIGS. 1, 2, 3A, and 3B.

Another alternative ball valve design (not shown) may include a valve,wherein the ball member (50) is disposed between seats in a two-piece ora three-piece ball valve body, which are well known in the industry. Theball member (50) may be installed in the valve cavity through the sideopening in the main body, prior to installation of an end member, whichmay have threaded ports or a flange connection for connecting to themain body. The housing cavity may be designed to accommodate upperand/or lower trunnions (56, 57) by having a cooperative groove on thetop and/or bottom inside surfaces of the valve body defining the cavity.

In another embodiment (not shown), the ball member may not contain theupper and/or the lower trunnions (56, 57), whereby the valve maycomprise a floating ball valve design. The upper end of the ball member(50) of the floating ball valve design may comprise a flush cavity toaccommodate the bottom or the insertable end of the valve stem. In thefloating ball valve, the ball member (50) may be held in place by thesealing elements (i.e., the seats) and the stem. Such floating ballvalve design is well known in the art. In the floating ball embodiment,the ball member may self-centering and is not prone to problems fromtolerance variations as, during operation, the ball member tends to movedownstream slightly, compressing and sealing against the seats.

Embodiments usable within the scope of the present disclosure alsorelate to methods of manufacturing the ball member (50). As describedabove, one manufacturing technique utilizes a milling machine, or anyother similar device, to cut the entire ball member (50) from a singleworkpiece (not shown), wherein the workpiece is typically a solid pieceof material, such as stainless steel, which is machined to form the ballmember (50). The workpiece in the described embodiment comprises thesame X, Y, and Z axes as the ball member (50).

Referring now to FIG. 7, one embodiment of the process of manufacturingthe ball member (50) according to the present disclosure is shown. Thefigure depicts a ball member (50) engaged with a milling machine (notshown) having a fly cutter (70) located above the ball member (50). Thefigure also designates local coordinates X, Y, and Z, relative to theball member (50), and universal coordinates, X1, Y1, and Z1, relative tothe milling machine and fly cutter (70). The local coordinates are fixedwith the ball member (50), wherein the X axis is always aligned with theaxis of rotation (X), the Z axis is always aligned with the longitudinalaxis (Z), and the Y axis is always located perpendicular to the both theX and Z axes. During the manufacturing process, the local coordinates,X, Y, and Z, change directions with respect to the universal coordinatesX1, Y1, and Z1 as the ball member (50) is rotated about the X and X1axes, which are aligned. The universal coordinates remain static,regardless of the movement of the ball member (50).

One embodiment of the manufacturing process incorporates the use of amilling machine having the capacity to rotate the workpiece about the X1axis and move the fly-cutter (70) along the Y1 and Z1 axes. A blankworkpiece is first engaged with a milling machine, having a spindle andtailstock along the X1 axis, which grip the workpiece on opposite sides,along the X axis of the workpiece.

At the initial stages of the manufacturing process, the local anduniversal coordinates have the same origin, with X, Y, and Z coordinatesbeing aligned with the X1, Y1, and Z1, coordinates respectively. Theinitial location of the fly cutter along the local coordinates is (0, 0,Z) and along the universal coordinates is (0, 0, Z1), wherein Z and Z1values are equal.

The first phase of the milling operations comprise descending therotating fly cutter (70) towards the origin along the Z and Z1 axis to avalue that is equal to the sum of the first radius (61 a) and the firstoffset distance (62 a).

The second phase comprises simultaneously: 1) rotating the workpiece, ata constant speed, 180 degrees counter-clockwise, about the X1 axis, 2)further descending the fly cutter towards the origin along the Z1 axis,moving a distance that is equal to the sum of the desired offsetdistances (62 a, 62 b), and 3) moving the fly-cutter along the Y1 axisaway from the origin for the first 90 degrees of rotation and thentowards the origin for the second 90 degrees of rotation, wherein thedistance of each motion is equal to the desired first offset distance(62 a). The above three steps initiate and terminate at the same timeand machine the first spherical segment (51 a). At this point, thesecond spherical segment (51 b) may be machined by repeating the firstand second phases of the milling operations.

The third phase of the milling operations comprise resetting therotating fly-cutter (70) above the ball member (50), opposite thestarting position of the second phase. As the second phase ends on saidopposite side, the fly-cutter may be reset by moving it away from theorigin along the Z and Z1 axis to a value that is equal to the sum ofthe second radius (61 b) and the second offset distance (62 b).

The fourth phase comprises simultaneously: 1) rotating the workpiece, ata constant speed, 180 degrees counter-clockwise, about the X1 axis, 2)descending the fly cutter towards the origin along the Z1 axis, moving adistance that is equal to the sum of the desired offset distances (62 a,62 b), and 3) moving the fly-cutter along the Y1 axis away from theorigin for the first 90 degrees of rotation and then towards the originfor the second 90 degrees of rotation, wherein the distance of eachmotion is equal to the desired second offset distance (62 b). The abovethree steps initiate and terminate at the same time and machine thesecond spherical segment (51 b). Although the method described abovediscloses rotating the workpiece 180 degrees about the X1 axis, otherembodiments of the ball member (50) may require a different method ofmanufacture, for example, that the workpiece be rotated more or lessthan 180 degrees, in order to meet the structural requirements of theball member (50). Similarly, although the method described abovediscloses moving the fly-cutter along the Y1 axis in specific directionsand at specific times during the manufacturing process, in otherembodiments of the manufacturing process, the fly-cutter may move alongthe Y1 axis at different times and different directions, depending onthe structural requirements of the ball member (50).

The throughbore (50) may be created by cutting a bore along the Z axis,using any known means, such as a different fly cutter, a drill, or alathe. The trunnions (56, 57) may also be machined by any known means,such as an appropriately sized fly cutter, a drill, or a lathe. Althoughdescribed last, the throughbore (50) and the trunnions (56, 57) may bemachined either at the beginning or the end of the manufacturing processof the ball member (50).

The ball member (50), as described above, provides operationalimprovements over valves utilizing typical ball members. FIGS. 1, 2, and3A depict the aforementioned ball member (50) in its open position,mounted within the housing cavity (24) formed by the valve housing (20)and the bonnet (22), as described above. The ball member (50) is adaptedto be rotated through about 90 degrees, whereby in the open position,the throughbore (55) may be aligned with said axial flow channels (21 a,21 b), as shown in FIG. 1, and in the closed position, the throughboremay be disposed transverse to the axial flow channels (21 a, 21 b), tocontrol the flow of fluid through the valve housing (20), as shown inFIG. 3B.

A pair of annular seats (30 a, 30 b) are supported by housing shoulders(28 a, 28 b) located about the interior ends of the fluid channels (21a, 21 b), wherein the shoulders (28 a, 28 b) support the seats (30 a, 30b) for engagement with the ball member (50). Due to the configuration ofthe ball member (50), the housing cavity (24), and the seats (30 a, 30b), the ball member (50) engages the seats with a variable force,depending on the angular position of the ball member (50) with respectto the seats (30 a, 30 b). Referring also to FIG. 6B, depicting anembodiment of the ball member (50), as the spherical segments (51 a, 51b) of the ball member comprise variable radii (65 a, 65 b) relative toits axis of rotation (X), the force with which the ball member (50)exerts on the seats (30 a, 30 b) varies with its angular position.Because the low surface areas (53 a, 53 b) surrounding the throughbore(55) have shorter radii (65 a, 65 b), the compressive forces with theseats (30 a, 30 b) are the smallest in the open valve position. As theradius (65 a, 65 b) of the ball member (50) increases while moving awayfrom the throughbore (55), the compressive forces between the ballmember (50) and the seats (30 a, 30 b) increase.

Therefore, as the ball member (50) is rotated toward the closed valveposition, the high surfaces (52 a, 52 b) of the ball member (50) contactadjacent surfaces of the seats (30 a, 30 b) with an increasing force,with maximum seat loading being achieved in the fully closed position ofball member (50). The amount of offset (62 a, 62 b) that is providedbetween the high surface areas (52 a, 52 b) and low surface areas (53 a,53 b) to enable this operation is determined experimentally, and to someextent, may be proportional to the size of the valve (10). As the sizeof the valve (10) increases, the extent to which the seats (30 a, 30 b)deflect increases, therefore the amount of offset (62 a, 62 b) betweeneach spherical segment (51 a, 51 b) and the axis of rotation (X) is alsoincreased.

Although each of the embodiments described above comprises a ball member(50) having offset spherical segments (51 a, 51 b), the ball member hasa symmetrical design, wherein the spherical segments (51 a, 51 b) aresymmetrically positioned about the axis of rotation (X). Furthermore,the ball member (50) is positioned centrally between the two seats (30a, 30 b), resulting in a balanced valve design, wherein the ball member(50) seals against both seats (30 a, 30 b) in the closed valve position.The balanced valve design results in an equal pressure being exertedupon each seat (30 a, 30 b), giving the ball member (50) additionalstructural support against excessive internal strains caused by highfluid pressures. Because of the progressively larger diameter, thetorque required to rotate the ball member (50) steadily increases, oncethe ball member comes into contact with the seats (30 a, 30 b). Sincethe force of contact is low for most of the valve cycle, increasingsignificantly as the ball member (50) reaches the closed valve position,a longer seat life is possible, since compressive and frictional forceson the seats (30 a, 30 b) are reduced as the ball member (50) is rotatedto its open valve position.

In the depicted embodiment of the present disclosure shown in FIG. 1,the seats (30 a, 30 b) and the dimensions of the aforementioned valveelements are so selected that, in the open position of the valve (10),the surfaces of the spherical segments (51 a, 51 b) contact the seats(30 a, 30 b) without causing significant flexure of the seats (30 a, 30b). This arrangement allows for minimal compression and, therefore,decreases wearing action caused by the ball member (50). Furthermore,because the two offset points (58 a, 58 b) are located in-line along thelongitudinal axis (Z) of the throughbore (55), the low surface areas (53a, 53 b), adjacent to the rims (66 a, 66 b) of the throughbore (55),comprise a symmetrical radius with respect to the axis (Z). This designenables the ball member to make even contact with the entire seat (30 a,30 b), resulting in uniform seat loading with the ball member (50).

In the closed valve position, located about 90 degrees from the openvalve position, the two offset points (58 a, 58 b) are located laterallywith respect to the seats (30 a, 30 b), which results in high surfaceareas (52 a, 52 b) having a progressively increasing radius (65 a, 65 b)with respect to the axis of rotation (X). This design may result in anuneven seat (30 a, 30 b) loading, wherein the portion of the seatslocated closest to the shoulder (54 a, 54 b) are compressed more orfurther than the portion located away from the shoulder (54 a, 54 b).Non-uniform compression may be compensated by seats (30 a, 30 b) havingadjustable or floating design, such as disclosed above and depicted inFIG. 4 or in U.S. Patent Application Publication No. 2010/0308247A1,which is incorporated herewith in its entirety.

The ball member (50) disclosed herein may also be used with other seatsknown in the industry, which adjust to a ball member (50) that makesuneven contact with the seats. For example, in another embodiment, theseats may be statically positioned between the housing shoulders (28 a,28 b) and the ball member (50), wherein the elastic and other propertiesof the sealing members allow uneven contact with a ball member (50),while maintaining a leak tight seal. Lastly, as certain embodiments ofthe ball member (50) comprise small offset distances (62 a, 62 b) andsmall shoulder (54 a, 54 b) heights, almost any commercially availableseat will function in conjunction with the ball member (50) of thecurrent disclosure.

While various embodiments usable within the scope of the presentdisclosure have been described with emphasis, it should be understoodthat within the scope of the appended claims, the present invention maybe practiced other than as specifically described herein.

What is claimed is:
 1. A method for manufacturing a ball member usablein a flow control valve, the method comprising: forming a first curvedportion of the ball member by: rotating a workpiece about 180 degreesabout an axis of rotation; rotating a cutting tool; and moving thecutting tool towards the axis of rotation along an axis of the cuttingtool to create a radius of the first curved portion that extends from apoint on the axis of the cutting tool that is offset from anintersection of the axis of the cutting tool and the axis of rotation;forming a second curved portion of the ball member by: rotating theworkpiece about 180 degrees about the axis of rotation; rotating thecutting tool; and moving the cutting tool toward the axis of rotationalong the axis of the cutting tool; and machining a bore through thefirst and second curved portions transverse to the axis of rotation. 2.The method of claim 1, wherein the rotating the workpiece about 180degrees about the axis of rotation, the rotating the cutting tool, andthe moving the cutting tool towards the axis of rotation along the axisof the cutting tool are performed simultaneously.
 3. The method of claim1, further comprising at least one of: machining the workpiece to form afirst cylindrical protrusion along the axis of rotation; and machiningthe workpiece to form a second cylindrical protrusion along the axis ofrotation opposite the first cylindrical protrusion.
 4. The method ofclaim 1, wherein the forming the first curved portion of the ball memberand forming the second curved portion of the ball member furthercomprises moving the cutting tool generally perpendicular to both theaxis of the cutting tool and the axis of rotation.
 5. The method ofclaim 4, wherein the moving the cutting tool generally perpendicular toboth the axis of the cutting tool and the axis of rotation comprisesmoving the cutting tool generally perpendicular to both the axis of thecutting tool and the axis of rotation away from a point of intercept ofsaid axes for about a first 90 degrees of rotation of the workpiece andtowards the point of intercept of said axes for about a second 90degrees of rotation of the workpiece.
 6. The method of claim 4, whereinthe moving the cutting tool towards the axis of rotation and the movingthe cutting tool generally perpendicular to both the axis of the cuttingtool and the axis of rotation further comprises forming a variableradius of the ball member relative to the axis of rotation.
 7. A methodfor manufacturing a ball member from a workpiece, the method comprising:connecting the workpiece to a rotating apparatus at a first connectionpoint of the workpiece and at a second connection point of theworkpiece; rotating the workpiece along a first axis; moving a rotatingcutting tool along a second axis toward the workpiece; cutting theworkpiece partially between the first connection point and the secondconnection point, thereby: forming a first surface extending partiallybetween the first connection point and the second connection point;forming a portion of a first protrusion on a first side of the firstsurface; and forming a portion of a second protrusion on a second sideof the first surface; moving the rotating cutting tool along the secondaxis away from the workpiece; further rotating the workpiece along thefirst axis; further moving the rotating cutting tool along the secondaxis toward the workpiece; further cutting the workpiece partiallybetween the first connection point and the second connection point,thereby: forming a second surface extending partially between the firstconnection point and the second connection point; forming an anotherportion of the first protrusion on a first side of the second surface;and forming an another portion of the second protrusion on a second sideof the second surface; and cutting a bore through the workpiece, whereinthe bore extends through the first surface and through the secondsurface.
 8. The method of claim 7, wherein the forming the first surfaceextending partially between the first connection point and the secondconnection point comprises forming the first surface extending partiallybetween the first connection point and the second connection point andextending partially around the first axis, and wherein the forming thesecond surface extending partially between the first connection pointand the second connection point comprises forming the second surfaceextending partially between the first connection point and the secondconnection point and extending partially around the first axis.
 9. Themethod of claim 7, wherein the rotating the workpiece along the firstaxis and the moving the rotating cutting tool along the second axistoward the workpiece comprise simultaneously rotating the workpiecealong the first axis and moving the rotating cutting tool along thesecond axis toward the workpiece, and wherein the further rotating theworkpiece along the first axis and further moving the rotating cuttingtool along the second axis toward the workpiece comprise furthersimultaneously rotating the workpiece along the first axis and movingthe rotating cutting tool along the second axis toward the workpiece.10. The method of claim 7, further comprising: moving the rotatingcutting tool along a third axis perpendicular to the first and secondaxes; and further moving the rotating cutting tool along the third axisperpendicular to the first and second axes.
 11. The method of claim 10,wherein the rotating the workpiece along a first axis, the moving arotating cutting tool along a second axis toward the workpiece, and themoving the rotating cutting tool along a third axis perpendicular to thefirst and second axes are performed simultaneously and wherein thefurther rotating the workpiece along a first axis, further moving arotating cutting tool along a second axis toward the workpiece, andfurther moving the rotating cutting tool along a third axisperpendicular to the first and second axes are performed simultaneouslyare performed simultaneously.
 12. The method of claim 10, wherein themoving the rotating cutting tool along the third axis perpendicular tothe first and second axes comprises: moving the cutting tool in a firstdirection along the third axis; and moving the cutting tool in a seconddirection along the third axis, opposite the first direction; andwherein the further moving the rotating cutting tool along the thirdaxis perpendicular to the first and second axes comprises: furthermoving the rotating cutting tool in the first direction along the thirdaxis; and further moving the cutting tool in the second direction alongthe third axis, opposite the first direction.
 13. The method of claim12, wherein the moving the cutting tool in the first direction along thethird axis comprises moving the cutting tool in the first directionalong the third axis for about a first 90 degrees of rotation of theworkpiece along the first axis, wherein the moving the cutting tool inthe second direction along the third axis comprises moving the cuttingtool in the second direction along the third axis for about a second 90degrees of rotation of the workpiece along the first axis, wherein thefurther moving the cutting tool in the first direction along the thirdaxis comprises further moving the cutting tool in the first directionalong the third axis for about a third 90 degrees of rotation of theworkpiece along the first axis, and wherein the further moving thecutting tool in the second direction along the third axis comprisesfurther moving the cutting tool in the second direction along the thirdaxis for about a fourth 90 degrees of rotation of the workpiece alongthe first axis.
 14. A method for manufacturing a ball member usable in aflow control valve, the method comprising: connecting a workpiece to arotating apparatus along an axis of rotation of the workpiece;simultaneously rotating the workpiece about the axis of rotation andmoving a rotating cutting tool toward the axis of rotation along asecond axis to form a first curved surface having a progressivelyshorter radius with respect to the axis of rotation, wherein the secondaxis is generally oriented perpendicular to the axis of rotation, andthe progressively shorter radius extends from a point on the second axisthat is offset from an intersection of the second axis and the axis ofrotation; moving the rotating cutting tool along the second axis awayfrom the workpiece; further simultaneously rotating the workpiece aboutthe axis of rotation and moving the rotating cutting tool toward theaxis of rotation along the second axis to form a second curved surfacehaving a progressively shorter radius with respect to the axis ofrotation; and cutting a bore through the workpiece, wherein one end ofthe bore extends through the first surface and the other end of the boreextends through the second surface.
 15. The method of claim 14, whereinthe simultaneously rotating the workpiece about the axis of rotationcomprises simultaneously rotating the workpiece about 180 degrees aboutthe axis of rotation, and wherein the further simultaneously rotatingthe workpiece about the axis of rotation comprises simultaneouslyrotating the workpiece about 180 degrees about the axis of rotation. 16.The method of claim 14, wherein the axis of rotation extends through theworkpiece between a first point and a second point of the workpiece,wherein the first curved surface and the second curved surface extend apartial distance between the first point and the second point.
 17. Themethod of claim 14, wherein the simultaneously rotating the workpieceabout the axis of rotation and moving a rotating cutting tool toward theaxis of rotation along a second axis further comprises moving therotating cutting tool along a third axis generally orientedperpendicular to both the axis of rotation and the second axis, whereinthe further simultaneously rotating the workpiece about the axis ofrotation and moving the rotating cutting tool toward the axis ofrotation along the second axis further comprises further moving therotating cutting tool along the third axis.
 18. The method of claim 17,wherein the moving the rotating cutting tool along the third axiscomprises moving the cutting tool in a first direction along the thirdaxis and then moving the cutting tool in a second direction along thethird axis, wherein the second direction is opposite the firstdirection, wherein the further moving the rotating cutting tool alongthe third axis comprises further moving the cutting tool in a firstdirection along the third axis and then further moving the cutting toolin a second direction along the third axis.
 19. The method of claim 18,further comprising: cutting the workpiece to form a first cylindricalprotrusion extending on a first side of the first and second surfaces;and cutting the workpiece to form a second cylindrical protrusionextending on a second side of the first and second surfaces.